1. Field of the Invention
This invention relates to automobile testing methods, and more particularly to the diagnostic testing of automobile electronics systems.
2. Description of the Prior Art
As the use of electronics to control and perform various automotive functions becomes more prevalent, the quick, accurate and comprehensive testing of automotive electronics systems has grown to be more of a problem. (The term "automobile" as used herein includes trucks and other vehicles having electronics systems analogous to those found in automobiles.) Currently available field test equipment is generally passive in nature. The testers monitor the outputs of various electronics systems in the automobile for a given operating condition, such as the motor idling, in an attempt to determine the cause of a malfunction. However, it may not be possible to determine the cause of many malfunctions without taking the automobile through a sequence of operating conditions, such as starting the engine and accelerating to a high speed, and simultaneously observing the condition of the electronics systems during the testing sequence. Available testers do not have any convenient mechanism for sequencing an automobile through a variety of operating conditions, and are generally limited in the number of different responses they can observe.
The inability to perform comprehensive diagnostic testing of electronics systems at the local site level can result in great inefficiencies. For example, it is often difficult to determine whether a particular problem resides in the engine or the transmission. Of transmissions which are shipped back to the factory for correction, the majority are returned with no problem having been located, while in most of the remainder the problem is corrected by a minor adjustment at the factory that could have been made in the field had the proper diagnostic equipment been available.
Another complicating factor in electronics testing is the proliferation of many different electronics systems for different makes of cars, among different models from the same automotive manufacturer, and even annual changes within the same model line. The different electronics systems are generally accompanied by different data formats that limit any particular testing unit to only a relatively small number of vehicles. Stocking a large number of different monitors to accommodate the various makes and models is expensive, inefficient and wasteful. However, due to the complexity of current electronics systems, it is difficult and sometimes impossible to perform adequate field service without the use of proper electronic testers.
The proliferation of different electronics systems is not limited to different makes and models; often the same model car will employ significantly different data format with each successive model year. This rapidly obsoletes testers which are dedicated to any particular make or model.
Another problem is the difficulty in simulating normal driving conditions within the confines of an automotive repair shop, while at the same time monitoring the various electronics systems to determine the location and nature of any malfunctions. Also, some automotive problems are intermittent and do not show up in a single test run. Current testers do not have the capability of monitoring a vehicle's performance over a long period of time and capturing the status of the various electronics systems when an intermittent malfunction occurs so as to enable effective diagnostic analysis.